Method for the manufacture of rib-piping



May 16, 1933. MORSETH METHOD FOR THE MANUFACTURE OF RIB PIPING FiledNov. 24, 1930 Patented May 16, 1933 UNITED STATES PATENT OFFICE LEIFMORSETH, OF HABLE, OSTRE AIKER NEAR OSLO, NORWAY, ASSIGNOR T0AKTIESELSKAPET PER K'UBE, NORSK MOTOR" & DYNAMOFABRIK, OF OSLO, NORWAYMETHOD FOR THE MANUFACTURE OF RIB-PIPING Application filed November 24,1930, Serial No. 497,768, and in Norway November 25, 1929.

My invention relates to ribbed tubing of the t pe consisting of a steamor gas pipe or tu e with ribs extending in substantially radialdirection and consisting of a continuous ribbon of sheet materialwrapped around the tube in the form of a spiral. The tube may beprovided with one or more spiral ribs arranged as a single or multiplethreaded screw. Previously ribbed tubing has'been made in two difierentways, either by cold wrapping or by hot wrapping of the rib formingband. Cold wrapping can easily be used where the radius of bending, i.e., the diameter of the piping is large, compared withthe width of theband, i. e., the height of the rib. The allowable maximum height of theribs will thus also in this case to a great extent depend upon theproperties of the rib material. In order to increase the height of theribs the base of the ribs has been made wider, for example, by providingthe ribbon with corrugations on the edge which contacts with the pipe,or by folding or bending over the edge of the bend, or finally byproviding outbent teeth on the rib.

As will be understood from the above, cold coiling has the disadvantageof limiting the height of the rib in relation to the diameter of thepiping.

If this disadvantage to some extent is limited by corrugations, thedisadvantage is introduced that only material of relatively littlethickness can be used. The mechanical durability of the rub thus becomesshort, as the ribs are very poorly adapted to be used where they aresubjected to the danger of rust development. A common disadvantage inall rib piping, Where the ribs have been wrapped on cold, is that thecon tact pressure between the pipe and the rib is very low, which ofcourse again reduces the conductivity.

By wrapping the band on hot the abovementioned disadvantages areeliminated, the material in the ribs becoming ductile to such an extentthat the necessary stretching of the outer edge and upsetting of theinner edge of the band will take place when the rib material is wrappedaround the pipe.

The method previously used when coiling of the band on hot, has been toheat the same by means of a gas flame previous to its coiling on to thepipe.

One object of the present invention is a method according to which therib material is electrically heated immediately before it is coiled onthe pipe.

According to the invention a number of obvious advantages are obtained,as for instance that the temperature of the rib material easily can bevaried as desired and that the heating of the rib material can takeplace all the way up to that point where it is brought in contact withthe pipe. By a suitable arrangement of the feeding contacts it is evenpossible to continue the heating of the rib material to such a degree atthe point where it is brought in contact with the pipe that it will bewelded to the pipe.

Other objects and novel features of the invention will appear from thefollowing description describing the method according to the inventionwith reference to the appended drawing showing the making ofsinlgle-threaded rib piping as an example on y.

In the drawing:

Fig. 1 is a view showing the manufacture of a ribbed tube, and

Fig. 2 is a section at the line IIII of Fig. 1.

In the drawing 1 denotes the tube, and 2 the coiled rib. During thewrapping the rib material 3 is fed on edge and through stretching means4 on to the surface of the tube from a suitable supply reel. At the pipegroper guiding means 5 may be arrange serving to keep the rib materialin a vertical osition in relation to the pipe and also ai ing in thestretching of the outer edge of the material. By means of contacts 7 and8 and suitable leads electric current from an electric source 6 is fedto the rib material. The contacts 7 and 8 may be of any suitableconstruction, as for instance roller contacts or sliding contacts. Thecontact 8 may be arrange in contact with the rib material 3, and thecontact 7if it is found desirable may be arranged within the pipe or onthe outside of the same or at some other suitable point. The pipe iscontinuously rotated and the material 3 moves in the direction indicatedby the arrow 9 in Fig. 2. The temperature which the rib material willobtain will depend on the electric power supplied from the source 6, thedistance between the contacts 7 and 8 and the rate of coiling, whichlatter is determined by the speed of rotation of the pipe. Where thecontact 7 is in contact with the strip 3, the heat is conducted to thepoint of contact thrbugh the strip and where the contact 7 bears uponthe pipe, the heat is conducted through the pipe itself.

The temperature at the place of coiling may thus be varied as desired byvarying one or more of these factors mentioned. Further it is possibleby suitable arrangement of the contact 7 to obtain more or lessconcentration of flow of current at the contact point between the riband the tube, thus making a variation of the temperature in the loweredge of the band in relation to the outer edge possible.

If multiple-threaded ribbed tubing is made, i. e., a tube wheresimultaneously two ormore bands suitably spaced adjacent to each otherare wrapped onto the tube, it is according to the invention possible touse single or multiple-phase current corresponding with the number ofthreads, each of the bands then preferably bein connected respectivelyto one each of t e oles of the source of polyphase current. T e use ofone pole in contact with the pipe may then be omitted.

By suitably choosing the above-mentioned heat-controlling factors it ispossible to deform the band in transverse section during the wrappingoperation, by stretching the outer edge and upsetting the inner edge insuch a wa that the contacting surface between the and and the tubingwill be sub-' stantially larger than that of the outer edge of the rib;thereby primarily providing for increased heat conductivity between thetube and the rib, and secondarily strengthening the mechanical stiffnessof the finished rib.

I have not shown or described specific apparatus for carrying out theinvention, these being for any technical trained man Very simple toconstruct on the basic of the showing in the description and claims.

I claim:

1. In the production of ribbed piping by' winding a ribbon helicallyupon a pipe, the process which comprises electrically heating that artof the ribbon immediately adjacent t e pipe while it is bein wound uponthe same, and maintaining sai ribbon under suflicient tension todecrease the thickness of that portion of the ribbon remote from ahelically wound rib formed from ribbon originally of substantiallyuniform thickness, the process of heating by electrical current the partof the ribbon which is to form the rib immediatel adjacent the pipewhile it is being woun around the same, and maintaining said ribbonunder suflicient tension to increase the thickness of that part of theribbon adjacent the pipe and to decrease the thickness of that portionof the ribbon remote from the pipe.

3. In the roduction of ri'bbed piping by winding a ri bon helically upona pipe, the method of electrically heating that part of the ribbonimmediately adjacent the pipe while it is being wound u on the same,which comprises conductin t e heating current'to the edge of the ri bonadjacent to the pipe, thereb to cause a higher degree of heating along te inner edge of the ribbon and a decreasing temperature towards theouter edge of the ribbon.

4. In the production of rib-pipin having a helically wound rib, theprocess 0 heating by electrical current the part of the ribbon which isto form the rib immediately adjacent the pipe while it is being woundaround the same, said electrical current bein conducted to the ribbonnear the edge a jacent to the pipe to cause a higher degree of heatingnear this edge and a decreasing temperature towards the other edge, tothereby effect an upsetting of the ribbon increasing in thicknesstowards the edge in contact with the pipe through the bending operation.

In testimony whereof I have signed my name unto this specification.

LEIF MORSETH.

